I think it looks something like:
7
The number 7 is written as seven.
The number 7.021 can be written in words as "seven point zero two one." If you need to express it in a more specific context, such as in mathematics or finance, it could also be referred to as "seven and twenty-one thousandths."
Seven.
0.87
7,000,000
7,000,000,000
sixity seven
0.7
Thirty Seven.
X _ 7
4,000,000,007
Seven